uboot: Apply patches outside container

When running inside a rootless Podman container on a SELinux-enabled
host, the `patch` command fails because it cannot copy SELinux labels
from the original file to the patched file.  This only happens patching
files that are located in a bind mount.

build-uboot.sh

@@ -5,14 +5,8 @@ set -e
 
 . ./config
 
+./patch-uboot.sh
 cd u-boot
-if [ ! -f .patched ]; then
-    for x in ../patches/uboot/*.patch; do
-        printf 'Applying patch %s ...\n' "${x##*/}"
-        patch -p1 < "${x}"
-    done
-    : > .patched
-fi
 cat configs/rpi_4_defconfig ../u-boot.config > configs/yellow_defconfig
 make yellow_defconfig
 CROSS_COMPILE=${target}- make